Disordered breathing is associated with a wide spectrum of respiratory conditions that involve disruption of the normal respiratory cycle. Although disordered breathing typically occurs during sleep, the condition may also occur while the patient is awake. Respiratory disruption can be particularly serious for patients concurrently suffering from cardiovascular deficiencies, such as congestive heart failure. Unfortunately, disordered breathing is often undiagnosed. If left untreated, the effects of disordered breathing may result in serious health consequences for the patient.
Various types of disordered respiration have been identified, including apnea, hypopnea, tachypnea, and periodic breathing. Apnea is a fairly common disorder characterized by periods of interrupted breathing. Apnea is typically classified based on its etiology. One type of apnea, denoted obstructive apnea, occurs when the patient's airway is obstructed by the collapse of soft tissue in the rear of the throat. Central apnea is caused by a derangement of the central nervous system control of respiration. The patient ceases to breathe when control signals from the brain to the respiratory muscles are absent or interrupted. Mixed apnea is a combination of the central and obstructive apnea types. Regardless of the type of apnea, people experiencing an apnea event stop breathing for a period of time. The cessation of breathing may occur repeatedly during sleep, sometimes hundreds of times a night and sometimes for a minute or longer.
In addition to apnea, other types of disordered respiration have been identified, including hypopnea (shallow breathing), tachypnea (rapid breathing), hyperpnea (heavy breathing), and dyspnea (labored breathing). Combinations of the respiratory cycles described above may be observed, including, for example, periodic breathing and Cheyne-Stokes respiration (CSR). Periodic breathing is characterized by cyclic respiratory patterns that may exhibit rhythmic rises and falls in tidal volume. Cheyne-Stokes respiration is a specific form of periodic breathing wherein the tidal volume decreases to zero resulting in apneic intervals. The breathing interruptions of periodic breathing and CSR are predominantly central in nature but may occasionally be obstructive in nature. Cheyne-Stokes respiration is frequently observed in patients with congestive heart failure (CHF) and is associated with an increased risk of accelerated CHF progression.
Although disordered breathing is more common during sleep, disordered breathing may also occur while the patient is awake. When disordered breathing occurs during sleep, the patient may briefly arouse in order to resume breathing. The frequent interruptions during sleep result in extremely fragmented sleep of poor quality. An adequate duration and quality of sleep is required to maintain physiological homeostasis. Untreated, disordered breathing may have a number of adverse health and quality of life consequences ranging from high blood pressure and other cardiovascular diseases to cognitive impairment, headaches, impaired driving skills resulting in increased vehicular accidents, and degradation of social and work related activities.